2. amps-preamps
  3. 184377-179812

Input impedance for Adcom GFA 555?

I’ve owned a pair of these amps since I bought them in the late 80s and now I’m adding a Vandersteen 2WQ subwoofer and to set the crossover I need to know the input impedance of the power amps. A couple Google searches lead me to an impass because I see both 100K ohms and 22K ohms listed. Note this is the original GFA555. Can anyone out there help me confirm the actual value? Thank you.

cantarkus
cantarkus OP
7 posts
 

Thanks again!

cantarkus OP
7 posts
 

Hey guys, I have a system up and running and so far I’m very pleased! Lots of tweaking left to do but I have a question right out of the shoot: I  have a grounding issue because I’m getting home from the sub. Step one in the owners manual is to ground the sub to either the main amp or preamp. Since I am I am bi-amping, I will ground it to the preamp. So…where is this the grounding connection on the 2WQ??I guess I’m being overly cautious - there is only one connection whose use is not clearly labeled so by process of elimination that must be it, but I’m just not sure. I would attach a photo but it’s not clear how to do that.

cantarkus OP
7 posts
 

Well, egg on my face, after getting down on my hands and knees and peering underneath what I called the RCA jack is actually just a binding post and there is a grounding symbol underneath it. Mystery solved!

 

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